// Sticky Header
          
    var top = $('header').offset().top + 100;
    $(window).scroll(function (event) {
      // what the y position of the scroll is
      var y = $(this).scrollTop();
        
      // whether that's below the form
      if (y >= top) {
        // if so, ad the fixed class
        $('header').addClass('fixed');
      } else {
        // otherwise remove it
        $('header').removeClass('fixed');
        }
    });